Harden builtins BuildResultFromMatchInfo and URIDecodeOctets

src/regexp.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Object = global.Object;
 // var $Array = global.Array;
 
 var $RegExp = global.RegExp;
@@ skipping 90 matching lines @@
 }
 
 
 function DoRegExpExec(regexp, string, index) {
   var result = %_RegExpExec(regexp, string, index, lastMatchInfo);
   if (result !== null) lastMatchInfoOverride = null;
   return result;
 }
 
 
-function BuildResultFromMatchInfo(lastMatchInfo, s) {
-  var numResults = NUMBER_OF_CAPTURES(lastMatchInfo) >> 1;
-  var start = lastMatchInfo[CAPTURE0];
-  var end = lastMatchInfo[CAPTURE1];
-  var result = %_RegExpConstructResult(numResults, start, s);
-  result[0] = %_SubString(s, start, end);
+// This is kind of performance sensitive, so we want to avoid unnecessary
+// type checks on inputs. But we also don't want to inline it several times
+// manually, so we use a macro :-)
+macro BuildResultFromMatchInfo(MATCHINFO, STRING)

[Yang, 2014/05/16 13:39:09]

I would use capital naming for the macro to make it clear at call sites that
it's a macro.

[Jakob Kummerow, 2014/05/16 13:43:04]

Done.

+  var numResults = NUMBER_OF_CAPTURES(MATCHINFO) >> 1;
+  var start = MATCHINFO[CAPTURE0];
+  var end = MATCHINFO[CAPTURE1];
+  var result = %_RegExpConstructResult(numResults, start, STRING);
+  result[0] = %_SubString(STRING, start, end);
   var j = REGEXP_FIRST_CAPTURE + 2;
   for (var i = 1; i < numResults; i++) {
-    start = lastMatchInfo[j++];
+    start = MATCHINFO[j++];
     if (start != -1) {
-      end = lastMatchInfo[j];
-      result[i] = %_SubString(s, start, end);
+      end = MATCHINFO[j];
+      result[i] = %_SubString(STRING, start, end);
     }
     j++;
   }
-  return result;
-}
+endmacro
 
 
 function RegExpExecNoTests(regexp, string, start) {
   // Must be called with RegExp, string and positive integer as arguments.
   var matchInfo = %_RegExpExec(regexp, string, start, lastMatchInfo);
   if (matchInfo !== null) {
     lastMatchInfoOverride = null;
-    return BuildResultFromMatchInfo(matchInfo, string);
+    BuildResultFromMatchInfo(matchInfo, string);
+    return result;

[Yang, 2014/05/16 13:39:09]

Why not make this part of the macro and call it something like
RETURN_NEW_RESULT_FROM_MATCH_INFO.

[Jakob Kummerow, 2014/05/16 13:43:04]

Done.

   }
   regexp.lastIndex = 0;
   return null;
 }
 
 
 function RegExpExec(string) {
   if (!IS_REGEXP(this)) {
     throw MakeTypeError('incompatible_method_receiver',
                         ['RegExp.prototype.exec', this]);
@@ skipping 22 matching lines @@
   if (IS_NULL(matchIndices)) {
     this.lastIndex = 0;
     return null;
   }
 
   // Successful match.
   lastMatchInfoOverride = null;
   if (global) {
     this.lastIndex = lastMatchInfo[CAPTURE1];
   }
-  return BuildResultFromMatchInfo(matchIndices, string);
+  BuildResultFromMatchInfo(matchIndices, string);
+  return result;
 }
 
 
 // One-element cache for the simplified test regexp.
 var regexp_key;
 var regexp_val;
 
 // Section 15.10.6.3 doesn't actually make sense, but the intention seems to be
 // that test is defined in terms of String.prototype.exec. However, it probably
 // means the original value of String.prototype.exec, which is what everybody
@@ skipping 261 matching lines @@
 
   for (var i = 1; i < 10; ++i) {
     %DefineOrRedefineAccessorProperty($RegExp, '$' + i,
                                       RegExpMakeCaptureGetter(i), NoOpSetter,
                                       DONT_DELETE);
   }
   %ToFastProperties($RegExp);
 }
 
 SetUpRegExp();